A) Field of the Invention
The present invention relates to a method of adjusting a record signal waveform of an optical disk, a method of storing record signal waveform adjustment data and an optical disk recorder, intending to reduce the amount of adjustment data to be stored in a memory.
B) Description of the Related Art
There are many recordable or rewritable optical disks: recordable or rewritable type CD's such as CD-R and CD-RW and recordable or rewritable type DVD's such as DVD-R and DVD-RW. Even if a laser beam is driven by the same record signal, record film sensitivity and heat conduction of each optical disk become different depending upon a disk type (not a format but a record film material, a maker, a product type number, and the like under the same format). Therefore, the front and back positions of each pit and land change with the disk type and the characteristics of reproduced signals such as jitter (shift in a time axis direction) and deviation (from a normal signal length) become different. It is necessary to adjust the time axis and level of a record signal waveform in accordance with the disk type in order to always ensure an optimum record quality.
Conventionally, adjustment data (so-called record strategy) for each disk type supplied by a maker is stored in a memory of an optical disk recorder. When data is recorded in an optical disk, the disk type is judged and the corresponding record strategy data is read from the memory to adjust the time axis, level and the like of a record signal waveform. A plurality of adjusting items are generally adopted to adjust a record signal waveform. A conventional optical disk recorder stores adjustment data of each item in the memory for each of disk types.
Along with prevailing recordable or rewritable type optical disks, the number of disk types (particularly the number of makers) of commercial disks is increasing and the amount of adjustment data stored in a memory is increasing. A record velocity magnification factor of an optical disk recorder can be set by a user. Since proper adjustment data changes with the record velocity magnification factor even with the same disk type, it is necessary to store adjustment data for each record velocity magnification factor in the memory. Recently, the number of record velocity magnification factors which can be set by a user is gradually increasing and the amount of adjustment data to be stored in the memory for each disk type is increasing. A large capacity memory is therefore required. One approach to reducing the amount of adjustment data is to group disk types together and use the same record strategy for each group. However, it is difficult to set suitable adjustment data for each of all items of each of all disk types in the same group.